The invention relates generally to devices used for preparing pipe end surfaces for welding of sleaves thereon and more specifically relates to devices used for shaving a portion of the outer diameter of the end of a pipe for preparation of welding.
Currently, the most popular way of transmitting natural gas is by the use of plastic pipes which are generally made of polyethylene, polyvinyl chloride or other types of plastic. These pipes are interconnected end to end by welding sleeves onto the ends of these pipes which in turn is welding onto the next length of pipe to be connected. The surfaces of the end of the pipe must be prepared to remove any trace of dirt and/or oxidation on the pipes so that a connecting sleeve can be effectively welded onto the end of a pipe. In order to remove the oxidized layer, currently the end of the pipe is prepared by either scraping manually using a sharp scraper blade and/or sanding using fine grit sand paper or in some instances, abrasive powder is used in order to abrade the end surface thereby removing the oxidized layer and any dirt thereon. Unfortunately, the effectiveness of these methods and the repeatability of obtaining a good clean oxide free surface prior to welding of a connecting sleave onto the end of the pipe has been rather poor. The quality of the surface preparation is depended upon how effective the operator is in scraping the surface and/or applying the sand paper or the abrasive grit, the length of time that the cleaning has taken place and the skill of the operator in preparing the surface. This leads to quality control issues in regard to the repeatability in preparing a good clean oxide free surface for welding of connecting sleeves onto the ends of plastic pipes.
Those skilled in the art are aware that leaks in natural gas pipe lines cannot be tolerated and can lead to disastrous consequences. Therefore, it is imperative that an oxide free clean surface is prepared in a consistent and repeatable manner so that a high degree of quality control can be exercised when welding connecting sleaves to the end of pipes.
A number of devices have been patented as follows:
U.S. Pat. No. 3,075,219 by J. V. Ott, patented Jan. 29, 1963, titled Pipe Cleaning Tool, describes a tool having a scraping blade which can be adjusted to accommodate various sizes of pipes.
U.S. Pat. No. 3,171,309 by A. J. Cloutier, patented Mar. 2, 1965, titled Device for Turning Male Ends on a Pipe, describes a device for use in forming male ends on tubular members.
U.S. Pat. No. 4,691,600 by Larry Carlson et al, patented Sep. 8, 1987, titled Pipe Shaver, describes a device having an elongated mandrel and a plurality of cutting tools used to shave the outer surface of a predetermined length of pipe.
Finally, U.S. Pat. No. 3,817,649 by Medney, patented Jun. 18, 1974, titled Pipe Scarfing Tool, describes a tool having a rotatable housing with a plurality of cutting blades therein which are rotated thereby scarfing and/or scraping the outside diameter of a pipe.
The disadvantage of all the above-mentioned devices is that they are unable to absorb any of the pipes extra thick portions or defective ovalization or out of roundness of the pipe. In other words, these devices do not make it possible to lift off a shaving or a very small portion of the out diameter thickness of the pipe regardless of the pipes deformations which include ovalization, thickness variations and/or outer deflections.
Finally, U.S. Pat. No. 4,744,123 by Le Testu et al, patented May 17, 1988 titled Device for Scraping the Outer Surface of a Tube, describes a device for shaving material from the outer surface of a pipe which is able to absorb defective ovalizations and/or variations in wall thickness and/or pipe deflections.
Unfortunately, in practise this device is unable to remove a very thin consistent showing in a uniform manner around the outer diameter of a pipe regardless of the deformities and/or ovalizations in the pipe. As well due to the complicated mechanical construction of the device it is difficult and time consuming to use and prone to mechanical breakdowns in the field. This device is more suitable for larger diameter pipes generally greater than 4 inches in diameter.
Therefore there is demand for device in the field which will quickly and easily shave off less than 10% of the wall thickness of the outer diameter of a pipe, near the pipe end for preparation for welding a connecting sleave thereto which will provide a very uniform clean surface in a reproducible manner at low costs and highest reliability.
The present invention a pipe shaver for removing a uniform layer of material from the outer diameter of a pipe, the pipe shaving comprises;
(a) a housing including a longitudinal axis;
(b) a cutting blade including a mounting means for mounting said blade to said housing, said blade including a cutting edge;
(c) a means for removably presenting said cutting edge to the out diameter of the pipe; and
(d) a means for moving said cutting edge around longitudinal axis along the outer diameter of said pipe for shaving a thin layer off the outer diameter of the pipe.
Preferably wherein said mounting means includes a blade guide for positioning a front face of said cutting blade at an angle theta of not less than 95 degrees relative to the pipe surface.
Preferably wherein said mounting means includes a blade guide for positioning a front face of said cutting blade at an angle theta not less than 114 degrees and not more than 120 degrees.
Preferably, wherein said mounting means includes a blade guide for positioning a front face of said cutting blade off set from said longitudinal axis at a blade position delta not equal to 0 degrees.
Preferably wherein said mounting means includes a blade guide for positioning a front face of said cutting blade off set from said longitudinal axis at a blade position delta greater than 5 degrees.
Preferably wherein said presenting means includes a means for normally biasing said blade radially inwardly onto the out diameter of a pipe.
Preferably, wherein said presenting means includes a lifting means for manually urging said blade radially outwardly away from said pipe.
Preferably, wherein said presenting means includes a blade housing for slidably receiving said blade therein, such that said blade moves up and down slidably in the radial direction.
Preferably, wherein said blade housing adapted to receive said housing means therein for biasing said blade radially inwardly.
Preferably, wherein said lifting means includes a pivoting lever connected at one end to said cutting blade, the other end projecting from said housing, such that pivoting said lever about a pivot point biases and lowers said cutting blade in a radial direction.